The conversion of forests to pastures is the most important human intervention that has shaped the natural landscape into the Anthropocene environment.The Qinghai-Tibet Plateau(QTP),which has both forest drought-lines...The conversion of forests to pastures is the most important human intervention that has shaped the natural landscape into the Anthropocene environment.The Qinghai-Tibet Plateau(QTP),which has both forest drought-lines and alpine treelines with specific ecotone structures,including isolated trees in treeless plant-covers that represent ever existed forest cover according to‘Lonely Tooth Hypothesis’,offers an excellent model in which to examine the extent and timing of human activity on the conversion of forest to pasture.The objectives of this paper are to review(1)palaeo-environmental records of the Early Holocene that indicate when forests were first converted to‘alpine meadows’,and(2)current records of the changing treeline ecotone in the region.‘Alpine meadows’of the QTP are part of the largest conversion of mountain forests into pastures worldwide.This change in forest cover is possibly a consequence of the agro-pastoral transition and the dawn of the Anthropocene on the QTP.To date,however,there is an interdisciplinary gap in knowledge of 5000 years between the palaeo-ecological and the archaeolocical and zoo-archaeological records.Rapid changes of the rural economy and the exodus from remote highland villages to down-country cities have diminished the age-old impacts of summer grazing and pasture management by fire;reforestation is obvious,but often seen exclusively as an effect of Anthropocene global warming.We believe that more interdisciplinary collaborations on the QTP are necessary to increase our understanding of the treelines of the Anthropocene in High Asia.展开更多
Deforestation remains one of the most imminent threats to biodiversity in the tropics.As such,its causes and dynamics need to be studied and understood to put a halt to further forest loss and degradation.In tropical ...Deforestation remains one of the most imminent threats to biodiversity in the tropics.As such,its causes and dynamics need to be studied and understood to put a halt to further forest loss and degradation.In tropical countries such as Uganda,agricultural expansion and wood fuel demand are its leading drivers.While the establishment of protected areas is a key tool in conserving remaining forest biodiversity,results indicate that current management does not sufficiently provide alternatives to forest resources utilised by households and income provided from timber and non-timber forest products.Beyond safeguarding ecosystems,protected areas need to ensure the sustainable socioeconomic development of adjacent communities for effective biodiversity conservation–however,both management and research often neglect to consider all dimensions.In this study,we analysed five decades of forest cover change in the Mount Elgon region,Uganda,by conducting a remote sensing analysis of its protected areas using Landsat MSS and TM data from 1973-2023 in combination with literature and subsequent interview analysis to consider both the ecological and socioeconomic dimension.We applied a random forest approach to differentiate forest and non-forest areas and carried out a pixel-based change detection analysis to differentiate temporal and spatial changes.Throughout the study period of 50 years,forest cover has evolved dynamically within the boundaries of the protected areas of Mount Elgon.A significant decline was observed in both Mount Elgon National Park with a loss of-5.98%(-46.83km²)and Mount Elgon Biosphere Reserve with a loss of-14.96%(-134.33km²).Our results showcase a cycle of deforestation and afforestation that could be tied to a series of development initiatives,re-demarcation of boundaries,changes in management and recurring evictions.Overall,the results lead to the conclusion that the lack of sustainable and efficient management and funding has fostered the rate of deforestation and accelerated ecological degradation in the region,but that existing problems are also rooted in the land tenure history of the region.We recommend the proper implementation of participatory and long-term management approaches on the ground and to address the land rights issue to contribute to both socioeconomic wellbeing and sustainable conservation outcomes.展开更多
At a global scale, tree growth in alpine treeline ecotones is limited by low temperatures. At a local scale, however, tree growth at its upper limit depends on multiple interactions of influencing factors and mechanis...At a global scale, tree growth in alpine treeline ecotones is limited by low temperatures. At a local scale, however, tree growth at its upper limit depends on multiple interactions of influencing factors and mechanisms. The aim of our research was to understand local scale effects of soil properties and nutrient cycling on tree growth limitation, and their interactions with other abiotic and biotic factors in a near-natural Himalayan treeline ecotone. Soil samples of different soil horizons, litter, decomposition layers, and foliage samples of standing biomass were collected in four altitudinal zones along three slopes, and were analysed for exchangeable cations and nutrient concentrations, respectively. Additionally, soil and air temperature, soil moisture, precipitation, and tree physiognomy patterns were evaluated. Both soil nutrients and foliar macronutrient concentrations of nitrogen(N), magnesium(Mg), potassium(K), and foliar phosphorus(P) decrease significantly with elevation. Foliar manganese(Mn) concentrations, bycontrast, are extraordinarily high at high elevation sites. Potential constraining factors on tree growth were identified using multivariate statistical approaches. We propose that tree growth, treeline position and vegetation composition are affected by nutrient limitation, which in turn, is governed by low soil temperatures and influenced by soil moisture conditions.展开更多
Climate warming is expected to advance treelines to higher elevations. However, empirical studies in diverse mountain ranges give evidence of both advancing alpine treelines as well as rather insignificant responses. ...Climate warming is expected to advance treelines to higher elevations. However, empirical studies in diverse mountain ranges give evidence of both advancing alpine treelines as well as rather insignificant responses. In this context, we aim at investigating the sensitivity and responsiveness of the near-natural treeline ecotone in Rolwaling Himal, Nepal, to climate warming. We analysed population densities of tree species along the treeline ecotone from closed forest stands via the krummholz belt to alpine dwarf shrub heaths （3700-4200 m） at 50 plots in 2013 and 2014. We quantified species - environment relationships, i.e. the change of environmental conditions （e.g., nutrient and thermal deficits, plant interactions） across the ecotone by means of redundancy analyses, variation partitioning and distance-based Moran＇s eigenvector maps. In particular, we focus on explaining the high competitiveness of Rhododendron campanulatum forming a dense krummholz belt and on the implications for the responsiveness of Himalayan krummholz treelines to climate change. Results indicate that treeline trees in the ecotone show species-specific responses to the influence of environmental parameters, and that juvenile and adult tree responses are modulated by environmental constraints in differing intensity. Moreover, the species - environment relationships suggest that the investigated krummholz belt will largely prevent the upward migration of other tree constrain the future response species and thus of Himalayan krummholz treelines to climate warming.展开更多
An important indicator of the rangeland health, associated with land degradation, is the ability of semi-natural rangelands to provide forage of sufficient quality for livestock production. In Qilian Mountains(Gansu P...An important indicator of the rangeland health, associated with land degradation, is the ability of semi-natural rangelands to provide forage of sufficient quality for livestock production. In Qilian Mountains(Gansu Province, NW China) biomass production and forage quality are dependent on the seasonality of precipitation and temperature; most of the precipitation falls during summer season, when sheep, goats and yaks graze mountain rangelands. To sustain the rangelands and to improve the management strategies, the assessment of the forage quality should be implemented. The purpose of this research was to study the response of biomass, forage quality and macronutrient content different levels of grazing intensity in Qilian rangelands. We sampled aboveground biomass in the growing seasons in 2012 and 2013 within spring/autumn or summer grazing regimes in two altitudinal zones below and above 3000 m a.s.l.(montane-subalpine and subalpine-alpine respectively). In order to estimate forage quality, biomass was sampled in 1 m × 1 m plots, assigned to the center of 10 ×10 m sites, fromwhich we collected different indicator parameters of rangeland health. Mineral and fiber content of forage biomass was estimated under different levels of grazing intensity with regard to the growing period. It was found that an increase in grazing intensity led to a decrease in dry matter weight. No linearity was observed in the relationship between nutritive value and grazing intensity. The highest fiber content(59.20 %) was found in plots mostly disturbed by grazing. The highest protein(16.30 %) and the lowest fiber(51.30 %) contents were associated with slightly grazing intensity. Concentrations of the mineral elements, such as Zn, P, K and S varied significantly and showed maximum values under low grazing intensity.展开更多
Soil erosion in mountain rangelands in Kyrgyzstan is an emerging problem due to vegetation loss caused by overgrazing. It is further exacerbated by mountain terrain and high precipitation values in Fergana range in th...Soil erosion in mountain rangelands in Kyrgyzstan is an emerging problem due to vegetation loss caused by overgrazing. It is further exacerbated by mountain terrain and high precipitation values in Fergana range in the south of Kyrgyzstan. The main objective of this study was to map soil erodibility in the mountainous rangelands of Kyrgyzstan. The results of this effort are expected to contribute to the development of soil erodibility modelling approaches for mountainous areas. In this study, we mapped soil erodibility at two sites, both representing grazing rangelands in the mountains of Kyrgyzstan and having potentially different levels of grazing pressure. We collected a total of 232 soil samples evenly distributed in geographical space and feature space. Then we analyzed the samples in laboratory for grain size distribution and calculated soil erodibility values from these data using the Revised Universal Soil Loss Equation (RUSLE) K-factor formula. After that, we derived different terrain indices and ratios of frequency bands from ASTER GDEM and LANDSAT images to use as auxiliary data because they are among the main soil forming factors and widely used for prediction of various soil properties. Soil erodibility was significantly correlated with channel network base level (geographically extrapolated altitude of water channels), remotely sensed indices of short-wave infrared spectral bands, exposition, and slope degree. We applied multiple regression analysis to predict soil erodibility from spatially explicit terrain and remotely sensed indices. The final soil erodibility model was developed using the spatially explicit predictors and the regression equation and then improved by adding the residuals. The spatial resolution of the model was 30 m, and the estimated mean adjusted coefficient of determination was 0.47. The two sites indicated different estimated and predicted means of soil erodibility values (0.035 and 0.039) with a 0.05 significance level, which is attributed mainly to the considerable difference in elevation.展开更多
基金support of the German Research Council(DFG)since 1976 and the cooperation with Sichuan University,Yunnan University,and the Institutes of the Chinese Academy of Sciences(CAS)in Kunming,Chengdu,Lanzhou,Xining,and Beijing.Udo Schickhoff is also grateful to the DFG for funding treeline-related research(SCHI 436/14e1)the National Natural Science Foundation of China(grant numbers U20A2080 and 31622015)Sichuan University(Institutional Research Fund,2021SCUNL102,Fundamental Research Funds for the Central Universities,SCU 2022D003)。
文摘The conversion of forests to pastures is the most important human intervention that has shaped the natural landscape into the Anthropocene environment.The Qinghai-Tibet Plateau(QTP),which has both forest drought-lines and alpine treelines with specific ecotone structures,including isolated trees in treeless plant-covers that represent ever existed forest cover according to‘Lonely Tooth Hypothesis’,offers an excellent model in which to examine the extent and timing of human activity on the conversion of forest to pasture.The objectives of this paper are to review(1)palaeo-environmental records of the Early Holocene that indicate when forests were first converted to‘alpine meadows’,and(2)current records of the changing treeline ecotone in the region.‘Alpine meadows’of the QTP are part of the largest conversion of mountain forests into pastures worldwide.This change in forest cover is possibly a consequence of the agro-pastoral transition and the dawn of the Anthropocene on the QTP.To date,however,there is an interdisciplinary gap in knowledge of 5000 years between the palaeo-ecological and the archaeolocical and zoo-archaeological records.Rapid changes of the rural economy and the exodus from remote highland villages to down-country cities have diminished the age-old impacts of summer grazing and pasture management by fire;reforestation is obvious,but often seen exclusively as an effect of Anthropocene global warming.We believe that more interdisciplinary collaborations on the QTP are necessary to increase our understanding of the treelines of the Anthropocene in High Asia.
基金The financial support by the Deutsche Bundesstiftung Umwelt (DBU)
文摘Deforestation remains one of the most imminent threats to biodiversity in the tropics.As such,its causes and dynamics need to be studied and understood to put a halt to further forest loss and degradation.In tropical countries such as Uganda,agricultural expansion and wood fuel demand are its leading drivers.While the establishment of protected areas is a key tool in conserving remaining forest biodiversity,results indicate that current management does not sufficiently provide alternatives to forest resources utilised by households and income provided from timber and non-timber forest products.Beyond safeguarding ecosystems,protected areas need to ensure the sustainable socioeconomic development of adjacent communities for effective biodiversity conservation–however,both management and research often neglect to consider all dimensions.In this study,we analysed five decades of forest cover change in the Mount Elgon region,Uganda,by conducting a remote sensing analysis of its protected areas using Landsat MSS and TM data from 1973-2023 in combination with literature and subsequent interview analysis to consider both the ecological and socioeconomic dimension.We applied a random forest approach to differentiate forest and non-forest areas and carried out a pixel-based change detection analysis to differentiate temporal and spatial changes.Throughout the study period of 50 years,forest cover has evolved dynamically within the boundaries of the protected areas of Mount Elgon.A significant decline was observed in both Mount Elgon National Park with a loss of-5.98%(-46.83km²)and Mount Elgon Biosphere Reserve with a loss of-14.96%(-134.33km²).Our results showcase a cycle of deforestation and afforestation that could be tied to a series of development initiatives,re-demarcation of boundaries,changes in management and recurring evictions.Overall,the results lead to the conclusion that the lack of sustainable and efficient management and funding has fostered the rate of deforestation and accelerated ecological degradation in the region,but that existing problems are also rooted in the land tenure history of the region.We recommend the proper implementation of participatory and long-term management approaches on the ground and to address the land rights issue to contribute to both socioeconomic wellbeing and sustainable conservation outcomes.
文摘At a global scale, tree growth in alpine treeline ecotones is limited by low temperatures. At a local scale, however, tree growth at its upper limit depends on multiple interactions of influencing factors and mechanisms. The aim of our research was to understand local scale effects of soil properties and nutrient cycling on tree growth limitation, and their interactions with other abiotic and biotic factors in a near-natural Himalayan treeline ecotone. Soil samples of different soil horizons, litter, decomposition layers, and foliage samples of standing biomass were collected in four altitudinal zones along three slopes, and were analysed for exchangeable cations and nutrient concentrations, respectively. Additionally, soil and air temperature, soil moisture, precipitation, and tree physiognomy patterns were evaluated. Both soil nutrients and foliar macronutrient concentrations of nitrogen(N), magnesium(Mg), potassium(K), and foliar phosphorus(P) decrease significantly with elevation. Foliar manganese(Mn) concentrations, bycontrast, are extraordinarily high at high elevation sites. Potential constraining factors on tree growth were identified using multivariate statistical approaches. We propose that tree growth, treeline position and vegetation composition are affected by nutrient limitation, which in turn, is governed by low soil temperatures and influenced by soil moisture conditions.
基金funded by Studienstiftung des deutschen VolkesGerman Research Foundation for funding(DFG,SCHI 436/14-1,BO 1333/4-1,SCHO 739/14-1)
文摘Climate warming is expected to advance treelines to higher elevations. However, empirical studies in diverse mountain ranges give evidence of both advancing alpine treelines as well as rather insignificant responses. In this context, we aim at investigating the sensitivity and responsiveness of the near-natural treeline ecotone in Rolwaling Himal, Nepal, to climate warming. We analysed population densities of tree species along the treeline ecotone from closed forest stands via the krummholz belt to alpine dwarf shrub heaths （3700-4200 m） at 50 plots in 2013 and 2014. We quantified species - environment relationships, i.e. the change of environmental conditions （e.g., nutrient and thermal deficits, plant interactions） across the ecotone by means of redundancy analyses, variation partitioning and distance-based Moran＇s eigenvector maps. In particular, we focus on explaining the high competitiveness of Rhododendron campanulatum forming a dense krummholz belt and on the implications for the responsiveness of Himalayan krummholz treelines to climate change. Results indicate that treeline trees in the ecotone show species-specific responses to the influence of environmental parameters, and that juvenile and adult tree responses are modulated by environmental constraints in differing intensity. Moreover, the species - environment relationships suggest that the investigated krummholz belt will largely prevent the upward migration of other tree constrain the future response species and thus of Himalayan krummholz treelines to climate warming.
基金the Robert Bosch Foundation (No.070610) for financial support of this joint international projectFinancial support of the PhD research project was provided by University of Hamburg’s Doctoral Funding Program (HmbNFG)merit scholarship program
文摘An important indicator of the rangeland health, associated with land degradation, is the ability of semi-natural rangelands to provide forage of sufficient quality for livestock production. In Qilian Mountains(Gansu Province, NW China) biomass production and forage quality are dependent on the seasonality of precipitation and temperature; most of the precipitation falls during summer season, when sheep, goats and yaks graze mountain rangelands. To sustain the rangelands and to improve the management strategies, the assessment of the forage quality should be implemented. The purpose of this research was to study the response of biomass, forage quality and macronutrient content different levels of grazing intensity in Qilian rangelands. We sampled aboveground biomass in the growing seasons in 2012 and 2013 within spring/autumn or summer grazing regimes in two altitudinal zones below and above 3000 m a.s.l.(montane-subalpine and subalpine-alpine respectively). In order to estimate forage quality, biomass was sampled in 1 m × 1 m plots, assigned to the center of 10 ×10 m sites, fromwhich we collected different indicator parameters of rangeland health. Mineral and fiber content of forage biomass was estimated under different levels of grazing intensity with regard to the growing period. It was found that an increase in grazing intensity led to a decrease in dry matter weight. No linearity was observed in the relationship between nutritive value and grazing intensity. The highest fiber content(59.20 %) was found in plots mostly disturbed by grazing. The highest protein(16.30 %) and the lowest fiber(51.30 %) contents were associated with slightly grazing intensity. Concentrations of the mineral elements, such as Zn, P, K and S varied significantly and showed maximum values under low grazing intensity.
基金a part of a joint Kyrgyz-German research project “The Impact of the Transformation Process on Human-Environment Interactions in Southern Kyrgyzstan”, funded by the Volkswagen Foundation, Germany, which had no impact on research or result dissemination
文摘Soil erosion in mountain rangelands in Kyrgyzstan is an emerging problem due to vegetation loss caused by overgrazing. It is further exacerbated by mountain terrain and high precipitation values in Fergana range in the south of Kyrgyzstan. The main objective of this study was to map soil erodibility in the mountainous rangelands of Kyrgyzstan. The results of this effort are expected to contribute to the development of soil erodibility modelling approaches for mountainous areas. In this study, we mapped soil erodibility at two sites, both representing grazing rangelands in the mountains of Kyrgyzstan and having potentially different levels of grazing pressure. We collected a total of 232 soil samples evenly distributed in geographical space and feature space. Then we analyzed the samples in laboratory for grain size distribution and calculated soil erodibility values from these data using the Revised Universal Soil Loss Equation (RUSLE) K-factor formula. After that, we derived different terrain indices and ratios of frequency bands from ASTER GDEM and LANDSAT images to use as auxiliary data because they are among the main soil forming factors and widely used for prediction of various soil properties. Soil erodibility was significantly correlated with channel network base level (geographically extrapolated altitude of water channels), remotely sensed indices of short-wave infrared spectral bands, exposition, and slope degree. We applied multiple regression analysis to predict soil erodibility from spatially explicit terrain and remotely sensed indices. The final soil erodibility model was developed using the spatially explicit predictors and the regression equation and then improved by adding the residuals. The spatial resolution of the model was 30 m, and the estimated mean adjusted coefficient of determination was 0.47. The two sites indicated different estimated and predicted means of soil erodibility values (0.035 and 0.039) with a 0.05 significance level, which is attributed mainly to the considerable difference in elevation.
